The document JEE Main Previous year questions (2016-20): Heat & Thermodynamics- 2 JEE Notes | EduRev is a part of the JEE Course Physics For JEE.

All you need of JEE at this link: JEE

**Q.43. One mole of an ideal monatomic gas is compressed isothermally in a rigid vessel to double its pressure at room temperature, 27°C. The work done on the gas will be: (2018)(1) 300 R ln 7(2) 300 R ln 6(3) 300 R ln 2(4) 300 RAns. **(3)

= 300R ln 2

(1) 772 J

(2) 2520 J

(3) 2100 J

(4) 420 J

Ans.

Given,

Q

η

= 1/6

and (COP)

(Cop)

So, (cop)

so w = 100 cal

Or w = 420 J

(1) 1

(2) 3

(3) 2

(4) 3/2

Ans.

⇒

(1) 5 × 10

(2) 2 × 10

(3) 1 × 10

(4) 0.5 × 10

Ans.

Resistance after temperature increases by 500°C = 220/2 = 110Ω

110 = 100 (1 + α500)

a = 2 × 10

(1)

(2)

**(3) **

**(4) Ans.** (3)

Equation of line BC

(Given : room temperature = 30°C, specific heat of copper = 0.1 cal/gm°C) (2017)

(1) 1250°C

(2) 825°C

(3) 800°C

(4) 885°C

Ans.

100 × 0.1 × (t – 75) = 100 × 0.1 × 45 + 170 × 1 × 45

10t – 750 = 450 + 7650

10t = 1200 + 7650

10t = 8850

t = 885°C

(1)

(2) 3PKα

(3)

(4)

Ans.

**Q.50. The temperature of an open room of volume 30 m ^{3} increases from 17°C to 27°C due to the sunshine. The atmospheric pressure in the room remains 1 × 10^{5} Pa. If n_{i} and n_{f} are the number of molecules in the room before and after heating, then n_{f} – n_{i} will be (2017)**

(1) 2.5 × 10^{25}

(2) –2.5 × 10^{25}

(3) –1.61 × 10^{23}

(4) 1.38 × 10^{23}

Ans. (2)

n

n

Change of number of molecules

n

≈ – 2.5 × 10

C

C

The correct relation between a and b is: (2017)

(1) a = 14b

(2) a = 28b

(3)

(4) a = b

Ans.

Let molar heat capacity at constant pressure = X

X

MC

C

For hydrogen; a = R/2

For N

a/b = 14

a = 14b

(1) 434J/kg-°C

(2) 378J/kg-°C

(3) 315J/kg-°C

(4) 476J/kg-°C

Ans.

Q given = Q used

0.2 × S× (150 – 40) = 150 × 1 × (40 – 27) + 25 × (40 – 27)

0.2 × S × 110 = 150 × 13 + 25 × 13

(1) 0.24

(2) 0.15

(3) 0.32

(4) 0.08

(1) 7/5

(2) 6

(3) 7/2

(4) 5/2

Ans.

**Q.55. A steel rail of length 5 m and area of cross section 40 cm ^{2} is prevented from expanding along its length while the temperature rises by 10°C. If coefficient of linear expansion and Young's modulus of steel are 1.2 × 10^{-5} K^{-}^{1} and 2 × 10^{11} Nm^{-2} respectively, the force developed in the rail is approximately : (2017)**

(1) 2 × 10^{7} N

(2) 2 × 10^{9} N

(3) 3 × 10^{-5} N

(4) 1 × 10^{5} N

F = yA ∝ Dt

= 2 × 10

= 9.6 × 10

(1) 6.6 × 10

(2) 0.96 gm

(3) 4 × 10

(4) 0.8 gm

Ans.

(1)

(2)

(3)

(4)

Ans.

Ans.

When key is at point

(1) 25°C; α = 1.85 x 10

(2) 60°C; α = 1.85 x 10

(3) 30°C; α = 1.85 x 10

(4) 55°C; α = 1.85 x 10

Ans.

Time period of pendulum,

Thus, the coefficient of linear expansion in pendulum clock = 1.85 x 10

**(2) (3) **

**(4) Ans** (2)

**(1) **

**(2) **

**(3) **

**(4) Ans.** (1)

Equation of line AB

(For maximum temperature)

(Condition for maximum temperature)

(1) Linear increase for Cu, linear increase for Si

(2) Liner increase for Cu, exponential increase for Si

(3) Linear increase for Cu, exponential decrease for Si

(4) Linear decrease for Cu, linear decrease for Si (2016)

Ans.

(1) 16.7 kJ

(2) 167.4kJ

(3) 4.2 kJ

(4) 8.4 kJ

Ans.

(1) 1/α

(2) 2α

(3) α/2

(4) α

Ans.

(1) 1.68 × 10

(2) 1.71 × 10

(3) 1.51 × 10

(4) 1.67 × 10

Ans.

heat required to freeze 5 kg water

= 5 × 336 × 10

= 1680 × 10

⇒ Q

for carnot's cycle

(1)

(2)

(3)

(4)

Ans.

Offer running on EduRev: __Apply code STAYHOME200__ to get INR 200 off on our premium plan EduRev Infinity!

188 videos|517 docs|265 tests